Adobe estimates Cyber Monday will reach $3 billion in sales for the first time this year, a 12 percent increase from 2014, making for the largest single day for digital sales in history.

JC Penney is starting its Cyber Monday sales on Sunday but plans to offer discounts throughout the week.

“If we run out in the store, we immediately go right online, and then some of the great key items we’ve had we run out online, too. But online is definitely a key part of the business,” a JC Penney spokesman said.

Stores, such as Best Buy, Target, Walmart and Amazon.com, are offering between 15 and 50 percent off for the biggest online shopping day of the year.

Some are also guaranteeing free shipping.

Bravin Taralkar, of West Des Moines, said he splits his holiday shopping between Black Friday and Cyber Monday.

“Online, mostly electronics, and in store, all apparel, things we can try,” he said.

The National Retail Federation estimates nearly 136 million people to shop over the weekend, up from under 134 million last year.